The PSID is a longitudinal survey of a nationally representative sample of U.S. families that began in 1968. With 34 waves of data collected on the same families and their descendents as of 2005, the PSID is a cornerstone of the data infrastructure for empirically based social science research in the U.S. Through its long-term measures of economic and social well-being, and based on its weighted representative sample of U.S. families, the study has compelled both researchers and policy makers to confront and learn from the dynamism inherent in social and behavioral processes. With support from NICHD, the PSID supplemented its core data collection with information on PSID parents and their children collected in 1997 and 2002. The Child Development Supplement provides researchers with a comprehensive, nationally representative, and longitudinal data base of children and their families with which to study the dynamic process of early life experiences. CDS-I collected data on 3,563 children aged 0-12 in 2,394 families. CDS-II was collected on these same children in 2002 when they were 5-18 years old (2,909 children and 2,017 PSID families). The current grant application proposes to collect new data on the CDS children and their families. Specifically, this application proposes to: 1) collect core PSID data in 2007 and 2009 for the 2,019 families of children who participated in the CDS;and 2) implement in 2007 a new study called "Transition into Adulthood," that will gather information from children aged 18 and older who participated in CDS. These two activities are part of the larger plan that, when taken together, will provide an unprecedented look at the health and well- being of children and their families from birth, through childhood, adolescence, and young adulthood for a nationally representative sample within the rich PSID data. These activities complement two of the new areas of emphasis within the mission of the Demographic and Behavioral Sciences Branch of NICHD: "Intergenerational Research" and "Children and Child Health-A Population Perspective." Long-term plans include the collection of "Transition into Adulthood" data for each wave of the PSID until all CDS children have reached at least age 25, and the collection of a third wave of the CDS in 2007. Support for these additional efforts will be sought through separate grant applications.